1. Field
The field of invention relates generally to blowout preventer (BOP) equipment, and specifically to creating redundancy in BOP equipment to prevent and reduce the need for downtime and repairs.
2. Description of the Related Art
BOP systems are hydraulic systems used to prevent blowouts from subsea oil and gas wells. BOP equipment typically includes a set of two or more redundant control systems with separate hydraulic pathways to operate a specified BOP function. The redundant control systems are commonly referred to as blue and yellow control pods. In known systems, a communications and power cable sends information and electrical power to an actuator with a specific address. The actuator in turn moves a hydraulic valve, thereby opening fluid to a series of other valves/piping to control a portion of the BOP.
At times, the hydraulic elements in each of these redundant systems may fail to operate as intended, and necessitate that the control system switch master controls from one pod to the other. At this point, the drilling operator loses redundancy in the system, because there is no functioning back-up pod. As a result, the operator may be required to suspend operations and pull the BOP stack from the sea floor for costly downtime and repairs.
One problem with creating redundancy in hydraulic systems is that hydraulic systems are typically hard-plumbed, and are not capable of being readily re-configured or repaired. Due to size and weight constraints, functionality of the control system has been limited in the industry to only the necessary functions, and internal hydraulic redundancy has not been built into existing systems.
Previous methods for addressing system redundancy include having multiple back-up systems. Remotely operated vehicles (ROV's) and acoustic control systems have been used as back-ups; they, however, require a different controls interface and often lead to a degradation in system performance. Thus, they are often a method of last resort.